Gases mixing apparatus

ABSTRACT

A gas and air mixing device receives a pressurised supply of a gas, drawing an air supply from the ambient environment and outputs a pressurised combined mixture of air and said gas. The device includes a turbine with a gases inlet and a gases outlet and a pump with an air inlet and an air outlet. A combined gases outlet receives gases from the gases outlet of the turbine and air from the air outlet of the pump. The combined gases outlet ouputs a combined flow of the gases. The turbine is configured to drive the pump.

BACKGROUND

[0001] 1. Field of the Invention

[0002] The present invention relates to devices for the mixing of airand oxygen in a medical environment.

[0003] 2. Summary of the Prior Art

[0004] It is often desirable to supply a patient or person with an airstream enriched in oxygen to a greater concentration than ambient air.For this purpose a supply of oxygen is mixed with a supply of air forbreathing by the patient.

[0005] Where a patient is capable of normal breathing, an air entrainermay be added to a breathing intake tube. The air entrainer includes anoxygen inlet nozzle receiving a high pressure oxygen supply from a highpressure oxygen supply source. An air inlet port is provided in the wallof the entrainer adjacent the nozzle outlet. High velocity oxygen flowthrough the nozzle outlet and into the conduit draws air into theconduit through the air inlet port. This air becomes mixed with theoxygen flow as it passes along the conduit to the patient. The mixingratio may be adjusted by adjusting the size of the air inlet opening.The passive air entrainer is effective where the conduit has nosignificant resistance to flow. The passive air entrainer is unable tooperate effectively where there is a significant flow resistance.

[0006] For example, where the patient requires positive pressure therapythe air entrainer is ineffective. Positive pressure therapy is presentlyconsidered desirable in treatment in a range of respiratory ailments.

[0007] In many situations it is desirable to humidify respiratory gasesprovided to a patient. Many devices used to humidify such gasesunavoidably add significant flow resistance to the breathing intaketube. Air entrainers that operate in the manner described above musttherefore be placed between the humidification device and the patient tooperate correctly. The consequence of this placement is that theentrained ambient air does not pass through the humidifier and is nothumidified.

[0008] To overcome this difficulty an alternative mixed air/oxygensupply apparatus is commonly used in which the supplied gases are drawnfrom a compressed air supply and a compressed oxygen supply. Each gas issupplied through a regulator valve. The relative flow rate of each gasis thereby adjustable and the flows undergo a simple combination into asupply conduit.

[0009] Alternatively a mixed air/oxygen supply apparatus known as ablender uses partial pressure to provide a pressurised source of air andoxygen, controlling the source pressure of each of the gases to bemixed. Such a device comes with a dial to set the oxygen concentrationof the new pressurised source. A blender is usually connected to aregulator valve with which the user can set the desired flow rate of theblended gas.

[0010] Both these systems can provide a high pressure air/oxygen mixturewhich can be used to provide positive pressure therapy and is suitableto supply gases via a humidifier. The disadvantage of these systems isthe need for a compressed air supply in addition to the compressedoxygen supply, and in the case of the blender, considerable cost.

SUMMARY OF THE INVENTION

[0011] t is an object of the present invention to provide an air/oxygenmixing device which at least goes some way towards overcoming the abovedisadvantages or will at least provide health providers with a usefulchoice.

[0012] In a first aspect the present invention may broadly be said toconsist in a gas and air mixing device for receiving a pressurisedsupply of a gas, drawing an air supply from the ambient environment andoutputting a pressurised combined mixture of air and said gascomprising:

[0013] a turbine having a gases inlet and a gases outlet,

[0014] a pump having an air inlet and an air outlet, and

[0015] a combined gases outlet receiving gases from said gases outlet ofsaid turbine and air from said air outlet of said pump and outputting acombined flow,

[0016] said turbine being configured to drive said pump.

[0017] Preferably said turbine comprises:

[0018] a first chamber having an oxygen inlet and an oxygen outlet and aturbine in said first chamber receiving oxygen from said oxygen inlet;

[0019] said pump comprises:

[0020] a second chamber having an air inlet and an air outlet, and

[0021] an impeller in said second chamber receiving air from said airinlet; and

[0022] a drive train connects between said turbine and said impeller.

[0023] Preferably each of the components is formed from medical gradeplastics, for example by injection moulding. Some forms of turbine inparticular may be difficult to form by injection moulding in one pieceand may be instead formed as two pieces combined by ultrasonic welding,fasteners, adhesive bonding, integral clipping or other equivalentarrangements. Some other parts may require strength or other propertiesnot obtainable with plastic and may be formed from another material suchas aluminium, magnesium or stainless steel.

[0024] Preferably the oxygen inlet is configured for connection with anoxygen wall outlet or a compressed oxygen bottle outlet.

[0025] Preferably said gas inlets and outlets may include adjustableflow dampers.

[0026] Preferably said adjustable flow dampers include a calibrationsystem corresponding with the proportion of air or oxygen in the mixedflow for at least one set oxygen inlet pressure.

[0027] Preferably said first chamber and said second chamber are back toback, said turbine and said impeller are co-axial, and said drive traincomprises a shaft, and both said turbine and said impeller are connectedto said shaft.

[0028] Preferably said shaft is an integrally formed extension from thecentre of said impeller, extending through a dividing wall between saidfirst chamber and said second chamber, into said first chamber, and saidturbine is mounted on said extension.

[0029] Preferably said first chamber is formed by a cover member fittedto said dividing wall enclosing said turbine.

[0030] Preferably said second chamber is formed from a cover, fitted tosaid dividing wall and enclosing said impeller, said second coverincluding an air inlet at the centre of its main face.

[0031] Alternatively said device is arranged axially, said turbinecomprising

[0032] an axial turbine having a gases inlet and gases outlet,

[0033] said pump comprising an axial pump receiving gases from saidgases outlet of said turbine and air from a separate air inlet, and

[0034] said combined gases outlet receiving gases from said pump andoutputting a combined flow;

[0035] with said turbine and pump being arranged in axial alignment andsaid turbine being configured to drive said pump.

[0036] Preferably said device includes a housing with a first sectionand a second section, said first section having said oxygen inlet andsaid oxygen outlet and housing a rotor of said turbine; and

[0037] said second section having an air inlet, an oxygen inlet and saidpump gases outlet, and

[0038] housing an impeller,

[0039] a drive train connecting between said rotor and said impeller.

[0040] Preferably each of the components is formed from medical gradeplastics, for example by injection moulding. Some forms of turbine inparticular maybe difficult to form by injection moulding in one pieceand may be instead formed as two pieces combined by ultrasonic welding,fasteners, adhesive bonding, integral, clipping or other equivalentarrangements. Some other parts may require strength or other propertiesnot obtainable with plastic and may be formed from another material suchas aluminium, magnesium or stainless steel.

[0041] Preferably the oxygen inlet of said first section is configuredfor connection with an oxygen wall outlet or a compressed oxygen bottleoutlet.

[0042] Preferably said gas inlets and outlets may include adjustableflow dampers.

[0043] Preferably said adjustable flow dampers include a calibrationsystem corresponding with the proportion of air or oxygen in the mixedflow for at least one set oxygen inlet pressure.

[0044] Preferably said first section and said second section are coaxialand concentric over at least part of their length, said turbine rotorand said impeller are co-axial, and said drive train comprises a shaft,and both said turbine and said impeller are connected to said shaft.

[0045] Preferably said shaft is an integrally formed extension from thecentre of said impeller, mounted concentrically within said first andsecond sections.

[0046] Preferably said first and second sections are connected in amanner which allows unrestricted flow of ambient air into said secondsection whilst remaining structurally sufficient.

[0047] To those skilled in the art to which the invention relates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the scope of the invention as defined in the appended claims. Thedisclosures and the descriptions herein are purely illustrative and arenot intended to be in any sense limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048]FIG. 1 is a cross sectional front elevation through an air oxygenmixer according to the present invention.

[0049]FIG. 2 is a front elevation of the air/oxygen mixer of FIG. 1.

[0050]FIG. 3 is a side elevation of the air/oxygen mixer of FIG. 1.

[0051]FIG. 4 is a perspective exploded view of the air/oxygen mixer ofFIG. 1.

[0052]FIG. 5 is a top view of the mixer of FIG. 1 as connected in useincluding the combined flow outlet and the oxygen inlet connection.

[0053]FIG. 6 is a perspective view of the air inlet portion of a secondchamber housing according to a preferred embodiment of the presentinvention with partial cutaway.

[0054]FIG. 7 is a perspective exploded view of an air/oxygen mixeraccording to another embodiment of the present invention.

[0055]FIG. 8 is a cross sectional exploded view of the air/oxygen mixerof FIG. 7.

[0056]FIG. 9 is a perspective view of the assembled air/oxygen mixer ofFIG. 7.

DETAILED DESCRIPTION

[0057] One preferred embodiment of the present invention is disclosed inthe Figures. It will be appreciated that significant variations may beapplied to this preferred embodiment without departing from the scope ofthe present invention.

[0058] Referring in particular to FIGS. 1, 2 and 5 the oxygen mixingdevice according to the preferred embodiment includes a first chamber 1enclosing a turbine rotor 2 and a second chamber 3 enclosing an impeller4. A shaft 5 extends from the impeller 4 into the first chamber 1. Theturbine rotor 2 is mounted on the shaft 5.

[0059] In one preferred form, the turbine is of a Pelton wheel type, andthe rotor 2 includes a plurality of peripheral cups formed asdepressions 8 in its annular face 9. Compressed oxygen is suppliedthrough an oxygen inlet 6. The compressed oxygen leaves the oxygen inlet6 as a jet and impacts the cups of turbine rotor 2, driving rotation ofturbine rotor 2. The air exits the turbine enclosure 1 through an oxygenoutlet 10. Rotation of the rotor 2 rotates shaft 5 and impeller 4. Theimpeller 4 is a centrifugal air pump impeller. Rotation of impeller 4draws air through an air inlet 13 adjacent the centre of impeller 4. Theair is spun outwards between the impeller blades to a peripheral exitzone 14 and exits by exit 15.

[0060] A flow combining connector is connected with the oxygen outlet 10and the air outlet 15. The flow combining connector comprises forexample a flexible tube Y-piece 16 with a first end 17 fitted overoxygen outlet 10 and a second end 18 fitted over air outlet 15, theflows combining through a third leg 19.

[0061] In the preferred embodiment of the invention the first chamber 1is formed between a first cover 30 and a dividing wall member 32 and thesecond chamber 3 is enclosed between a second cover 34 and the dividingwall member 32. The dividing wall member 32 is a substantially circulardisk and includes an annular flange 38 extending from one face tosupport the rim of cover 30 and an annular flange 36 extending from itsother face to support the rim of cover 34. The dividing member 32includes a central aperture 40 receiving the shaft 5 therethrough. Anannular flange 42 surrounding aperture 40 extends from the air chambersurface of dividing member 32, and a similar annular flange 44 extendsfrom the oxygen chamber face of member 32. The flanges provideadditional bearing support for the shaft 5 and thrust bearing surfacesfor the impeller 4 and rotor 2. Additional bearings may be used betweenthe flanges 42 and 44 and the shaft 5 to provide a longer life product.The air chamber cover 34 includes air inlet 13 as an open short tube 50extending from the centre of its main face. The oxygen chamber cover 30includes oxygen outlet 6 as an open short tube 52 extending from thecentre of its main face.

[0062] Accordingly, in the preferred embodiment of the present inventionthe device is comprised of six components—the first cover 30, the secondcover 34, the dividing wall member 32, the impeller (with integral shaft5), the turbine 2 and the flow combining connector 16.

[0063] It should be appreciated that substantial variation in the actualconstruction is possible without departing from the scope of theinvention, and advantageous variations may include integrating the flowcombining connector 16 with the covers 30 and 34 (for example byproviding the outlet passages 10 and 15 as a combination of the cover 30or 34 respectively and the dividing wall 32, and leading to a commonlocation to combine as a single outlet connector). Other variations mayinclude using other forms of turbine for extracting energy from the highpressure oxygen flow, and/or other forms of impeller for creating theair flow.

[0064] Another modification may include the provision of an inlet airdamper on air inlet 13. An example of an appropriate adapter is depictedin FIG. 6 where air inlet tube 13 is partially enclosed by covering faceend 62. A cap 64 is fitted over the inlet tube 50, and retained in placeby channel 55 fitting over protrusions 68 from the cylindrical surfaceof inlet tube 50. The cap 64 includes a cylindrical body and an enclosedend 69. The enclosed end 69 includes a tapering aperture 70 with agraduated scale marked around its outer perimeter.

[0065] In use the orientation of the cap 64 on the inlet tube 50determines the size of the inlet opening by the intersection between theaperture 70 and the uncovered portion of the end of tube 50. Thegraduated scale of aperture 70 may be calibrated for a set oxygen inletpressure with a scale corresponding to the proportion of air resultingin the air/oxygen mix. The indicator relative to the scale maybe theedge 72 of the covered in portion 62 of the end of tube 50. The cap 64is rotatable on the tube 50 by sliding of protrusions 68 within channel65 to vary the amount of opening of the air inlet.

[0066] The device is illustrated in use in FIG. 5. A compressed oxygensupply tube 82 is connected with the short oxygen supply tube of housing30 via a connector 80. The flow combining connector 16 is connected witha breathing tube 20. When the compressed oxygen supply is started thisspins turbine rotor 2 in its passage through the first chamber to outlet10. Rotor 2 spins impeller 4 causing the impeller 4 to draw air into thesecond chamber 3 through inlet 50 and expel the air through outlet 15.The outlet flows combine in connector 16 and exit to breathing conduit20 under pressure.

[0067] A second preferred embodiment of the present invention isdisclosed in FIGS. 7, 8 and 9. It will be appreciated that significantvariations maybe also be applied to this second preferred embodimentwithout departing from the scope of the present invention.

[0068] The second embodiment is an axial arrangement. It includes anaxial flow turbine and an axial flow pump. The axial flow turbine andpump are arranged end to end. The turbine includes a rotor or impeller97, and the pump includes an impeller 98, with the turbine rotor 97arranged to drive the pump impeller 98.

[0069] The turbine impeller 97 and the pump impeller 98 are located on acommon shaft. A first housing surrounds the turbine impeller 97. Thefirst housing includes an oxygen inlet 90 and an oxygen outlet 92. Asecond housing is coaxial with the first housing, and is concentric withthe first housing over a part of their length where the two housingsoverlap. The second housing is greater diameter than the first housingat this overlap. The second housing thus has, centrally, an inlet foroxygen that has passed through the turbine, and an annular air inlet 100surrounding the outlet end of the first housing.

[0070] The shaft 96 is supported so as not to impede flow either side ofthe impellers. Struts 92 protuding from the inner surface of the oxygeninlet casing support the shaft at the turbine end and similar struts 93at the fan end. These struts can be shaped aerodynamically to reduceresistance to flow past them and to have positive effects on flowcharacteristics either side of the impellers.

[0071] High pressure oxygen flowing through the oxygen inlet must passby the axial turbine impeller 97 thereby imparting a force that willrotate the shaft. This forced rotation is transmitted to the axial fanimpeller 98. The rotation of the fan impeller, which is larger diameterthan the outlet end of the first housing, sucks ambient air through theair inlet 100 where it becomes mixed with oxygen that has passed throughboth the turbine and fan blades. The mixture of gases is then driventhrough gases outlet 99 by the pressure created by the fan impeller 98.

[0072] So for example the device may receive an oxygen supply at 50 psiabove ambient pressure and an air supply at ambient pressure, receivingapproximately 20 litres of oxygen per minute and extracting energy fromthe oxygen flow to drive the air pump. In turn the air pump sucks in theambient air and supplies it at its outlet at for example 2 psi aboveambient pressure and at a flow of 20 litres per minute, providing acombined flow from outlet connector 99 of 40 litres per minute at 2 psistatic pressure at approximately 60% Oxygen.

[0073] It will therefore be appreciated that the oxygen supply sideremains under pressure from its supply source and the air supply side ispositively driven by the pump impeller. This makes the device lesssusceptible to circuit back pressures than a passive air entrainer,while eliminating the need for a compressed air supply.

1. A gas and air mixing device for receiving a pressurised supply of agas, drawing an air supply from the ambient environment and outputting apressurised combined mixture of air and said gas comprising: a turbinehaving a gases inlet and a gases outlet, a pump having an air inlet andan air outlet, and a combined gases outlet receiving gases from saidgases outlet of said turbine and air from said air outlet of said pumpand outputting a combined flow; said turbine being configured to drivesaid pump.
 2. A mixing device as claimed in claim 1 wherein, saidturbine comprises: a first chamber having an oxygen inlet and an oxygenoutlet and a turbine in said first chamber receiving oxygen from saidoxygen inlet; said pump comprises: a second chamber having an air inletand an air outlet, and an impeller in said second chamber receiving airfrom said air inlet; and a drive train connects between said turbine andsaid impeller.
 3. A mixing device as claimed in claim 2 wherein theoxygen inlet is configured for connection with an oxygen wall outlet ora compressed oxygen bottle outlet.
 4. A mixing device as claimed inclaim 2 wherein said air inlet includes an adjustable air flow damper.5. A mixing device as claimed in claim 4 wherein said adjustable airflow damper includes a calibration corresponding with the proportion ofair or oxygen in the mixed flow for at least one set oxygen inletpressure.
 6. A mixing device as claimed in claim 2 wherein said firstchamber and said second chamber are back to back, said turbine and saidimpeller are co-axial, and said drive train comprises a shaft, and bothsaid turbine and said impeller are connected to said shaft.
 7. A mixingdevice as claimed in claim 6 wherein said shaft is an integrally formedextension from the centre of said impeller, extending through a dividingwall between said first chamber and said second chamber, into said firstchamber, and said turbine is mounted on said extension.
 8. A mixingdevice as claimed in claim 7 wherein said first chamber is formed by acovet member fitted to said dividing wall enclosing said turbine.
 9. Amixing device as claimed in claim 8 wherein said second chamber isformed from a cover fitted to said dividing wall and enclosing saidimpeller, said second cover including an air inlet at the centre of itsmain face.
 10. A mixing device as claimed in claim 1 wherein said deviceis arranged axially, said turbine comprising: an axial turbine having agases inlet and gases outlet, said pump comprising an axial pumpreceiving gases from said gases outlet of said turbine and air from aseparate air inlet, and said combined gases outlet receiving gases fromsaid pump and outputting a combined flow; with said turbine and pumpbeing arranged in axial alignment and said turbine being configured todrive said pump.
 11. A mixing device as claimed in claim 10 wherein saiddevice includes a housing with a first section and a second section,said first section having said oxygen inlet and said oxygen outlet andhousing a rotor of said turbine; and said second section having an airinlet, an oxygen inlet and said pump gases outlet, and housing animpeller; a drive train connecting between said rotor and said impeller.12. A mixing device as claimed in claim 10 wherein the oxygen inlet isconfigured for connection with an oxygen wall outlet or a compressedoxygen bottle outlet.
 13. A mixing device as claimed in claim 10 whereinsaid air inlet includes an adjustable air flow damper.
 14. A mixingdevice as claimed in claim 13 wherein said adjustable air flow damperincludes a calibration corresponding with the proportion of air oroxygen in the mixed flow for at least one set oxygen inlet pressure. 15.A mixing device as claimed in claim 11 wherein said first section andsaid second section are coaxial and concentric over at least part oftheir length, said turbine rotor and said impeller are co-axial, andsaid drive train comprises a shaft, and both said turbine and saidimpeller are connected to said shaft.
 16. A mixing device as claimed inclaim 15 wherein said shaft is an integrally formed extension from thecentre of said impeller, mounted concentrically within said first andsecond sections.
 17. A mixing device as claimed in claim 16 wherein saidfirst and second sections are connected in a manner which allowsunrestricted flow of ambient air into said second section through anannular opening between overlapping portions of said first section andsaid second section.